Carburetor



Aug. 23, 1938. s. F. HUNT GARBURETOR Filed Sept. 17, 1934 3 Sheets-sheet 1` IN V EN TOR.

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Si. F. HUNT CARBURETOR Filed Sept. 17, 1934 3 Sheets-@Sheet 2 R.. @WM/ mu M WH IFI. m@ C 5@ Y. B

CARBURETOR Filed Spt. 17, 1934 3 SheebSf-Sheet 5 INVENTOR. conf /fw/f BYQ@ ATTORNEY; I

Patented Aug. 23, 1,938

`ra'rlazlv'r OFFICE: y

CARBURETOR Scott F. Hunt, ,South Bend, Ind.. assignor to o Bendix Products Corporation, `South Bend,

Ind., a corporation of Indiana l Application September 17, 1934,ASerial No. 744,328 15 `Claims. (Cl. 2151-39) This invention relates to carburetors and more particularly to means for proportioning the amount of air admitted to the cylinders of an internal combustion engine, in accordance with manifold suction and Yengine temperature.

Internal combustion engines using liquid fuel are ordinarily equipped with carburetors which proportion the fuel to air ratio under various operating conditions. This is generally done by means of a choke valve, operably positioned in the air inlet passage of the `carburetor, so that the amount- `of air admitted under various operating conditions may be decreased by actuating the choke valve to partially close the air inlet passage. It is known in this art to actuate the ,choke valve manually; that is, by means of a manually operable connection designed to close the choke valve, while the choke valve is returned to its open position by resilient or gravity actuated means upon release of the manually operable means.

It is, however, desirable to automatically vary the richness of the mixture supplied to the engine in accordance with the variations in temn g5 perature of the engine, and the speed of the Temperature responsive means, such as a bimetallic thermostatic element, operably connected to the choke valve maybe employed herein to control the position of the choke valve in accordance with the temperature of the engine.

It i's also desirable to control the position'of the choke valve in accordance with the vacuum obtaining in the intake manifold. For this purpose applicant employs novel differential fluid pressure actuated means communicating with the main carbureting passage on either side of the throttle valve, and operably connected'with the choke valve in such a manner as to modify ,i0 theaction of the thermostat.

.As will be pointed out in more detail later, applicantfs novel differential fluid pressure actuated means comprises a member operable to restrict the flow of air bypassing the throttle valve when high suction is exerted in the manifold, and operable to permit an increasing quantity of air to bypass the throttle valve as, the vacuum isY destroyed.

An object of the present invention is therefore 50 to provide an automatic chpke mechanism, operable by the engine variables, manifold suction and engine temperature, whereby the most desirable and economical combustible mixture will be supplied by thecarburetor under al1 operating conditions of the engine.

Another object of the invention is to provide a built-in automatic choke mechanism, which will accurately and quickly proportion the quantity of air admitted to the engine, so as to produce the most satisfactory operation of the en- 5 gine during starting Vand warming up operations.

A still further object of the invention is to provide means.` operable upon a decrease in the manifold vacuum and/or other variables, to increase the quantity of air bypassing the throttle 10 valve to prevent the engine from stalling.

Another object of the invention resides in the provision of means for increasing the charge of combustible mixture supplied to the engine, when it is onerating'ata temperature below its normal '15 operating temperature.

il. still further object of the invention is the incorporation of an automatic choke, fast idle mechanism, and non-stalling device entirely enclosed in the body of the carburetor, so as to be v20 less susceptible to maladjustments in service, and to provide a simple mechanism having a minirhum of moving parts for controlling the combustible mixture supplied to the engine.

Another object of the invention is to provide 25 a novel choke actuating mechanism entirely enclosed within the body of the carburetorl Other objects and advantages of this invention'will be apparent from the following detailed description, together with the illustrative embodi- 3U ments thereof in the accompanying drawings, submitted for purposes of illustration only, and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.

In the drawings, wherein similar reference/ characters refer to similar parts throughout the4 several views:

Figure 1 is a longitudinal sectional view of a' carburetor equipped with a device of the present 40 ving the relative position of the parts when the engine is running and is cold; A

Figure 6711s al view similar to. Figure 4 showing 55 the relative position of the parts preparatory to cranking the engine when it is hot;

Figure 7 is a view similar to Figure 4 showing the relative position of the parts when the engine is running and is hot;

Figure 8 is a longitudinal view, partly in section, of a modied form of the invention;

Figure 9 is a plan view of a further modification, wherein a double-barreled carburetor is equipped with a device of the present invention;

Figure 10 is a longitudinal sectional view showing one position of the choke actuating mechanism shown in Figure 9; and

Figure 11 is a View showing another position of the choke actuating mechanism shown in Figure 10.

Referring more particularly to Figure 1, there is shown for illustration, a carburetor having an upper or air horn section I0 and a lower or throttle body section I2.

The air horn section I0 comprises an air inlet passage I4, in which a choke valve I6, preferably of the unbalanced type and provided with a spring-pressed poppet relief valve I1, is pivotally mounted on ashaft I8 journalled in the walls of the air inlet passage I4. A boss or housing 20 formed on one 'side of the air inlet passage I4, and receiving one end of the choke shaft I8, houses a portion of the choke valve actuating mechanism, to be more particularly described hereinafter. The air horn section I0 is provided with a flange 22 forming a float chamber cover. v

The lower or throttle body section I2 comprises a main carbureting passage 24, fitted with a secondary venturi 26. A primary venturi 28 is suspended in the main carbureting passage `24, and supported therein by a iin 38, in such a position that it Vdischarges at the ymost restricted section of the secondary venturi 26. A main fuel discharge nozzle 32 projects through the fin 30 and discharges at the most restricted section oi' the primary venturi 28. A conventional fuel reservoir 34 supplies fuel`to `the main fuel discharge nozzle 32 under a constant head.

.The main carbureting passage 24 receives a mixture of air and fuel, and discharges said mixture to the intake manifold (not shown), under the pumping action of the pistons reciprocating within the cylinders of the engine. The ow of the combustible mixture through the main carbureting passage 24 is normally controlled, in the usual manner, by a throttle valve 36 mounted on a throttle shaft 38, journalled in the walls of the throttle body section I2. Fuel for idling purposes is supplied in the known manner from the fuel reservoir 34, through a duct 40 terminating in a port 42 immediately posterior to the throttle valve 36 when in closed position. Air for idling purposes is supplied through a port 44, immediately anterior to the throttle and communicating with the port 42. ment screw 46 is provided to adjustably restrict the port 42 to increase or decrease the idling speed of the engine.

Applicants novel choke valve actuating mechanism comprises'a bell crank having arms 48 and 58, fixed to the choke shaft I8 and enclosed in the housing 20. plate 52, which carries a choke shaftbearing 54, to support one end of the choke shaft I8.' The arm 48 is provided with a pin 66 projecting through a semicircular shaped slot 58 in the plate 52, and positioned to be actuated by one end of a bimetallic thermostat 60. The other An idling adjust` The housing 20 is closed by a` end of the thermostat 60 is fixed to a stud 63, enclosed in a casing 62, adjustably clamped to the housing 20 by a plurality of screws 64. For purposes of illustration the thermostat is shown as heated by an electric coil 66 positioned within the casing 62. It is understood, however, that the thermostat may be heated by other means such as those disclosed in my copending applications Serial No. 718,633, led April 2, 1934, and Serial No. 744,329, iled September 17, 1934.

A cylinder 68 fixed in the air horn section Ill and communicating with the interior of the housing 26, is received within an enlarged bore formed in a longitudinal boss 10 in the throttle body section I2. A passageway 12, in the lower end of boss 10, communicates with the main carbureting passage 24 posterior to the throttle valve 36. A port 14 in the walls of the cylinder 68 serves to interconnect the interior of the cylinder 68 with the passageway 12.

u A second port 16 in the walls of the cylinder 68 connects with a passageway 18, which communicates with the main carbureting passage 24 anterior to the throttle valve 36.

A hollow spool-shaped valve member 80, having a small vent 8| in the lower part of the section of reduced outer diameter, is slidably mounted within the cylinder 68 and is yieldingly urged toward the upper end of the cylinder by a light coiled spring 82. 'Ihe spring 82 engages a section of the valve of reduced internal diameter 84. A hollow plunger 86, slidable within the spoolshaped valve 80, is operably connected to the arm 58 by a linkage 88.- The hollow plunger 86 is provided with a small vent 98 designed to be obstructed by the section of reduced internal diameter 84 of the valve member 80.

The operation of this device is as follows: When the engine is cold, the thermostat 60 will have rotated in the counterclockwise direction, as viewed in Figure 2, thereby rotating the arm 48 in the counterclockwis direction, to close the choke valve I6, and rotating the arm 50 to lift the plunger 86. This position of the parts is shown in Figures 1, 2 and 4, in which it will be noted that the spool-shaped valve 80 is urged to the upper end of the cylinder 68 by the spring 82.

When the engine is cranked, the choke valve I6 being heldin the closed position by the thermostat 68, a relatively high suction is exerted on the fuel discharge nozzle 32, to draw a quantit-y of fuel therefrom. The fuel mixes with air admitted through the relief valve I1, positioned in the choke valve I6, to produce a combustible mixture in the main carbureting passage 24, anterior to the throttle valve 36. Since the spoolshaped valve' 86 is in the upper end of the cylinder 68, free communication is established between the passages 18 and 12. The combustible mixture is therefore drawn up the passageway 18 into the cylinder 68, downwardly in the cylinder 68 (between the walls of the cylinder and the section of reduced outer diameter of the 'Ihe spool Valve 80 is thereupon urged 75 sectionpartially closes the passageway 12, and

a decreased quantity of combustible mixture bypasses the throttle valve 36. During this period of operation a combustible mixture is supplied through the idling passages 44 and 42, so that the additional charge supplied through the passageway 12 will produce a fast idle, to prevent the engine from stalling while it is cold.

When the spool-shaped valve member moves downwardly in the cylinder 68 to the position shown in Figure 5, the vent 90 in the plunger 8B becomes exposed above the top of the valve member 80. Since the vents 8| and 90 are of substantially the same size, the partial vacuum existing .within the spool-shaped valve member 80 andthe lower portion of the cylinder 6B is destroyed. The valve member 80 will then be held temporarily in equilibrium.

As the engine continues to run, the thermostat 60 will become heated, and tend to coil more tightly upon itself, thereby decreasing the force urging the choke valve I6 toward the closed position. As the air entering the air inlet passage |41 strikes against the unequal areas of the choke valve I6 on either side of the choke shaft l0, it will tend to rotate the valve i6 to open it. As the choke valve |6 is-gradually opened, the crank armv 50 is rotated in the clockwise direction as viewed in Figure 5, so that the plunger B6 :ls moved downwardly in the valve member 00. The vent 00 is then closed by the section of reduced internal diameter 04 of the valve member Bil, and air is withdrawn from the interior of the valve member 00, whereupon itwill be moved downwardly inthe cylinder t0, to reduce the quantityA of combustible mixture supplied to the engine through the passageway 12. This process is repeated until the engine is running at normal operating temperature, at which time the choke i valve i6 will be completely open as 4shown in Figurer?. The vent 90 in the plunger t@ is then cliosedby the section of reduced internal diameter tt of the valve member 00, and the valve member 80 is drawn downwardly to the bottom of the cylinder 63 by the suction exerted through the passageway 12 and the vent 0l. lit will be noted that in this position the enlarged upper portion of the valve member 80 closes off the passageway 10 `so that no communication is established between the passageways 12 and 10.

llgure 6 shows the relative position of the parts when the engine has been running at normal operating temperature and has been stopped. It will be noted that the choke valve i6 is in the full open position; that the plunger 06 -is extended into the valve member B0, and that the valve member 00 is held in the upper position by the spring' 82. In this position, communication is established between the passageways 12 and 18 so that a combustible mixture will be bypassed beyond thethrottle valve 36 to assist in starting the engine. Assoon as the. engine has started running on its own power, the interior of valve member 80 and the lower portion `of the cylinder 68 will be evacuated and the valve member 80 will be urged downwardly against the force of the spring 82.

It will be observed that this device operates as an anti-stall device. If the engine slows down -below normal idling speed, when the throttle the spring 82 will force the valve member 00 upwardly in the cylinder 68. Communication is then established between the passageways 12 and 10, whereupon an additional quantity of combustible mixture is supplied posterior to the throttle valve 36, `which will prevent the engine from stalling. As soon as the engine begins running again at normal idlingL speed, air will be withdrawn from the interior of the valve member 80, and it will again move to the bottom of cylinder 68, as shown in Figure 7, to cut oft' the excess charge of combustible mixture bypassing the throttle valve 36.

The modification disclosed in Figure 8 is similar inl principle to the embodiment disclosed in Figure 1. To avoid repetition the corresponding parts have been given the same numerals with the addition of 100. The vacuum actuated piston mechanism is different in many respects from the embodiment of Figure l. A cylinder |0| is provided with an outlet |03, communicating with the main carbureting passage |24, posterior to the throttle valve |36. The cylinder l0| is also provided with a plurality of apertures |05 communicating with the main carbureting passage |24, anterior to the throttle valve |36, through a port |01. A hollow piston |09 having a small vent in the end thereof is slidably mounted in the cylinder |0| and actuated by a link H3. The link H3 is connected by an overrunningconnection l2 to another link H5 connected to the choke valve shaft H8 by an arm lig. By. reason of the overrunning connection H2, force can be transmitted in `only one direction,v that is, the piston l00 can exert force on the choke valve U6 tending to open it, but the choke valve cannot force the piston |09 downwardly. The operation oi this device is substantially smilar to the operation of the embodiment illustrated in Figure 1. choke valve H6 isurged to the closed position by the thermostat |60, and the piston` |09 is lifted to the position shown in Figure 8 by the links M3 and H5. In this position of the piston i09, a bypass is established around the throttle valve Hit through the port |01, apertures |05, and the outlet |03.A A combustible mixture is thus bypassed around the throttle to assist in starting the engine.

When the engine has started and warms up, the force of the thermostat |60, urging the choke valve il toward closed position, is decreased. The force of the air entering the air inlet ||4 'urges the unbalanced valve IIB toward open position. As the choke valve opens, the piston |09 is drawn by suction downward in the cylinder |0I, and progressively closes the apertures |05 so that a decreasing quantity of combustible mixture is allowed to bypass the throttle valve. It thus appears that as the engine progressively warms up, the amount of mixturepermitted to bypass the throttle is progressively decreased, giving a slower idling speed, and when the engine is running at normal operating temperature the piston |00 rests upon the bottom ofthe cylinder |0| to completely close the outlet |03. When the piston |09 closes the outlet |03, all of the mixture for idling purposes is supplied through theidling passages' |42 and |44. The vent operates to assist in the smooth operation of the device by preventing the sudden increase of suction in the piston |00 which would otherwise occur as the piston approached its lowerrnost position.

Figures 9, 10 and 11 show a modication wherein this invention is applied to a double-barrelled carburetor having a single air inlet passage.

The cylinder |53 and piston IBI controlling the bypass around the throttle valve are positioned in the throttle body section, and communicate with each barrel of the carburetor, posterior and anterior to the throttle valve.

Applicant's novel connection between the piston |6| and the choke valve ||8 is contained entirely within the air horn section. It comprises a link of irregular shape and of streamlined section. A portion |53 of the link |5| is 4 arcuate in shape and projects through a slot cut in the face of the unbalanced choke valve H6. A projection |55 is pivotally engaged by a bracket |56 xedto the upper face of the valve ||6 near the choke shaft-|||l. 'I'he arcuate section |53 is designed to close the slot in the face of the choke valve when in closed position, as shown in Figures 9 and l0.

The link |5| has a vertically extending section |51 and a horizontally extending section |59 designed to transmit force from the piston ISI to the choke valve III and vice versa. As shown in Figure 11, the vertical section |51 contactsl a portion of the valve to prevent it from rotating beyond the vertical or full open position.

The'operation of this device is substantially similar to the operation of the device illustrated in Figure 1, and therefore will not be discussed in detail.

While several illustrative embodiments of the invention have been illustrated and described in detail, it is not intended that the invention shall be limited to those embodiments, nor otherwise, than by the terms of the following claims.

I claim:

1. In a carburetor, a throttle, a choke valve,

temperature responsive means' iniluencing the position of the choke valve, and means including a cylinder, a hollow spool-shaped spring pressed plunger and a piston controlled in part by the position of the temperature responsive means and in part by suction beyond the throttle for introducing a charge of combustible mixture beyond the throttle.

2. In a, carburetor having a main carbureting passage, a throttle valve, a pressure responsive choke valve, temperature responsivelmeans influencing the position of the choke valve, and means including a cylinder communicating with the carbureting passage on either side of the throttle valve and a pressure responsive ternperature controlled piston slidably mounted in the cylinder for introducing fuel mixture beyond the throttle.

3. A carburetor having a main induction passage, a throttle and an unbalanced pressure responsive choke valve mounted therein, temperature responsive means urging the choke valve toward one extremeiposition when cold, and means including a .cylinder and n, hollow spring pressed piston jointly controlled by the position of the choke valve and pressure in the induction pas-- sage posterior to the throttle valve for introducing a charge of combustible mixture into the induction passage posterior to the throttle valve. v i 4. In a carburetor having a main carbureting passage, a throttle valve, an unbalanced choke valve, temperature responsive means operably connected to the choke valve, a fluid pressure diierential actuated motor including a cylinder connected to the main 'carbureting passage on either side of the throttle, a piston invsaid cylinder, and connecting means between the piston and the choke valve whereby said motor may inmain carbureting passage on either side of the throttle valve when said choke valve is actuated by said temperatureresponsive means.

5. In a carburetor, a main induction passage, a choke valve, a throttle valve,Y thermostatic means to actuate the choke valve, a fluid actuated motor including a cylinder communicating with the induction passage on either side of the throttle'valve, a piston in said cylinder, and connecting means between a portion of said motor and the thermostatic means whereby said motor modifies the action of said thermostatic means.

6. In a carburetor having a main carbureting passage, a throttle valve, an unbalanced choke valve, temperature responsive means urging the choke valve closed when cold, a fluid motor including a cylinder communicating with the main carbureting passage on either side of the throttle valve, a hollow spool-shaped piston slidably mounted within the cylinder, yielding means urging the piston to one extreme position, a vent in a portion of the piston operable to subject the v interior of the piston and a portion of the cylinder to suction existing in the main carbureting passage posterior to the throttle valve, and connecting means between the piston and the choke valve. I

7. In a carburetor having a main carbureting passage, a throttle valve, an unbalanced choke valve, temperature responsive means urging the` choke valve closed when cold, a fluid motor including a cylinder communicating with the main carbureting passage on either side of the throttle valve, ak hollow spool-shaped piston slidably mounted within the cylinder, yielding means urging the piston to one extreme position, a vent in a portion oi' the piston operable to subjectvthe interior of the piston and a portion of the cylinder to suction existing in the main carbureting passage posterior to the throttle valve, a hollow plunger slidable within said piston, a vent in a portion of said plunger operable to destroy the vacuum within said piston and a portion of the cylinder under certain operating conditions, and

connecting means between the plunger and the.

choke valve.

8. In a carburetor having a main carbureting passage, a throttle valve, a choke valve, thermostatic 'means operably connected to the choke valve, a cylinder formed integral with the main carbureting passage, connecting means between the -cylinder and the carbureting passage on either side of the throttle valve, a hollow spoolshaped piston slidably mounted within the cylinder, yielding means urging the piston'to one extreme position, a vent in a portion of the piston operable to subject the interior of the vpiston and a portion of the cylinder to the pressure existing in the main carbureting passage posterior to the throttle valve, a portion -of said piston being of reduced internal diameter, a hollow plunger slidable within said piston, a vent in a. portion of the plunger designed to be closed under certain operating cnditions by the portion of said piston of reduced internal diameter, and connecting means between said plunger and said choke valve.

9. In a carburetor having a main carbureting passage, a throttle valve, a choke valve having a spring pressed poppet relief valve, therm'ostatic means operably connected to the choke valve,- a motor including a cylinder formed integral with the main carbureting passage, connecting means between the cylinder and the carbureting passage on eitherV side of the throttle valve, a hollow spool-shaped piston slidably mounted within the cylinder, yielding means urging the piston to one extreme position, a vent in a portion of the piston operable to subject the interior of the piston and a portion of the cylinder to the pressure existing inv the main carbureting passage posterior to the throttle valve, a portion of said piston being of reduced internal diameter, a hollow plunger slidable within said piston, a vent in a portion of the plunger designed to be closed under certain operating conditions by the `ilportion 0I said piston of reduced internal diameter,and connecting means between said plunger and said choke valve whereby the motor iniiuences the position of the choke valve and the thermostatic means influences theposition of the piston whereby a charge of combustible mixture is bypassed beyond the throttle valve until the choke valve approaches substantially full open position.

10. A carburetor having a main induction pasf sage, a throttle and choke valve mounted therein, and means jointly controlled by the position of the choke valve and pressure in the induction passage posterior to the throttle valve for introducing a charge of combustible mixture into the induction passage posterior to the throttle valve.

11. Ina carburetor, an induction passage, choke and throttle valves therein, a 'main fuel nozzle, a conduit bypassing the throttle valve, and a-temperature actuated valve including a cylinder, a piston slidable inthe cylinder yield-l ingly urged by suction posterior to the throttle valve toward the closedlpositioncontrolling said conduit.

12. In. a carburetor, an induction passage,

, choke and throttle valves' therein, a main fue! nozzle, a conduit bypassing the throttle valve, a bypass valveincluding a cylinder adjacent and parallel to the induction passage and a piston slidable in the cylinder yieldingly urged by suction posterior to the throttle valve toward the closed position controlling said conduit, and temperature responsive means operably connected to the choke valve and to the bypass valve for influencing the operation of the bypass valve.

13. In a carburetor, a choke valve, a throttle valve, a mixing chamber -between said valves,

' means to supply fuel and air to the mixing chamber, a mixture bypass around the throttle valve, and valve means subjected to pressures 'beyond the throttle valve and operably connected to the choke valve to open the bypass when the choke i valve approaches the substantially closed position and a. predetermined pressure beyond the throttle valve is exerted on the bypass.`

14. In acarburetor, an induction passage, a

' pressure responsive choke valve. temperature responsive means for controlling said choke valve, a throttle controlling the induction passage, a bypass for fuel mixture around the throttle, a

plunger controlling the bypass and urged by suc'. tion posterior to the throttle toward a position where it closes the bypass, and an overrunning connection between the choke valve and the plunger.

15. In a carburetor, an induction passage, a pressure responsive choke valve, temperature responsive means for controllingthe same, a throt# tle in said induction passage, a .bypass for fuel mixture around the' throttle, a plunger controlling the bypass and urged by suction posterior tothe throttle toward a position where it closes the bypass, and a connection between the lchoke valve and plunger operative -when the choke valve is closed to move the plunger to a'position where it opens the bypass.

SCOTT F. HUNT.V 

